Debt is not the only contributor to a potential collapse though. I think there are other more likely natural collapses that can occur but they wont be limited to America. The world is over populated and over polluted. From a population stand point alone I don't see how the earth can continue to support such a high population. As resources become scarce it doesn't take a genius to see that things will get very interesting. However, I'm more interested in just how close we are to an actual tipping point in some of these calamity situations. It is quite easy to be a pessimist but at the same time I wonder just how justified in holding on to some of these beliefs. Maybe I'm wrongly underestimating humanities response to such situations